But we must not jump to the conclusion that the hypothalamus itself is the 'seat' of emotion. That would leave out of account the ideational aspect, and would reduce emotion to 'nothing but' visceral reactions. William James came in fact very close to this position when, in 1884, he published an article that launched the famous James-Lange theory of emotions. In a nutshell, the theory said that in those situations which require visceral reactions to cope with them (e.g., accelerated heartbeat for running away from danger), the feeling that one's heart races is the emotion. The heart does not race because we are frightened; we are frightened because the heart races; and we do not weep because we feel sad, we feel sad because we weep. It is the perception of one's own visceral reactions which lends emotional colouring to experience. The visceral reaction itself is automatic and unconscious, either innate or acquired by past experience.
The James-Lange theory gave rise to endless controversies which even today, eighty years after its launching, have not completely died down. In 1929 Walter Cannon -- a pioneer in this field -- seemed to have given the coup de gr�ce to it, when it was shown that emotional behaviour persists even after the connections between viscera and brain had been severed. This and other experimental evidence brought the theory into disrepute.* James' doctrine that emotions are 'nothing but' visceral reactions has certainly proved untenable; but the very fact that the doctrine was so hard to kill shows that it contained a hard core of truth -- the fact, driven home by common, everyday observation, that diffuse bodily sensations from internal processes which are not under voluntary control form an essential component of all emotional experience. Cannon's own theory of emotions (the Cannon-Bard theory) laid decisive emphasis on the bodily changes in 'emergency reactions' to hunger, pain, rage and fear, mediated by adrenal hormones and the autonomic nervous system. But he shifted the focus of attention from the visceral to the cerebral mechanisms in the hypothalamus which control them, and regarded the bodily changes as expressions rather than causes of emotional feeling.
* Nevertheless, quite recently Mandler has shown that even the seemingly decisive evidence (Cannon's famous 'five points') is open to a different interpretation: 'Although visceral changes are essential for the initial establishment of emotional behaviour, on later occasions the emotional behaviour may prove to have been conditioned to external stimuli, and may occur both without visceral support and -- in some form -- prior to it. . . . Cannon's argument that emotional behaviour may be present in the absence of visceral activity will probably have to be restricted to saying that it will only be present when intact visceral structures and responses have previously mediated the link between environmental conditions and emotional behaviour. . . . Visceral response is important for the establishment, but not for the maintenance, of emotional behaviour.' [12]
The Cannon-Bard theory was in its turn criticised by Lashley and others; but at this point the subject becomes too technical. To sum up, we may safely conclude that emotions are 'overheated drives' (due to internal and/or external stimulations) which are temporarily -- or even permanently -- deprived of an adequate outlet; the dammed-up excitement stimulates visceral and glandular activity, affecting circulation, digestion, muscle-tone, etc.; and 'the reverberations of the total organism can then register centrally as felt emotion' (Herrick [13]). Or, to quote Mandler's more recent survey of the subject: 'As far as the physical background of emotion is concerned, we can agree with commonsense that some sort of internal, visceral response accompanies the production of emotional behaviour.' [14] And there is further evidence that these visceral responses depend on archaic structures in the brain whose fundamental pattern has undergone but little change in the whole course of evolution 'from mouse to man' (MacLean).
The Three Brains
After this historical excursion, let us return to the question how these archaic structures, and the archaic feelings to which they give rise, get along with the brand-new structures and functions in our brains. The following excerpts lead straight into the problem; they are from a medical paper by Professor Paul MacLean, who fathered the so-called Papez-MacLean theory of emotions:
Man finds himself in the predicament that Nature has endowed him essentially with three brains which, despite great differences in structure, must function together and communicate with one another. The oldest of these brains is basically reptilian. The second has been inherited from lower mammals, and the third is a late mammalian development, which in its culmination in primates, has made man peculiarly man. Speaking allegorically of these three brains within a brain, we might imagine that when the psychiatrist bids the patient to lie on the couch, he is asking him to stretch out alongside a horse and a crocodile. The crocodile may be willing and ready to shed a tear and the horse to neigh and whinny, but when they are encouraged to express their troubles in words, it soon becomes evident that their inability is beyond the help of language training. Little wonder that the patient who has personal responsibility for these animals and who must serve as their mouthpiece is sometimes accused of being full of resistances and reluctant to talk. . . . [15] The reptilian brain is filled with ancestral lore and ancestral memories and is faithful in doing what its ancestors say, but it is not a very good brain for facing up to new situations. It is as though it were neurosis-bound to an ancestral superego. In evolution one first sees the beginning of emancipation from the ancestral superego with the appearance of the lower mammalian brain, which Nature builds on top of the reptilian brain. . . . Investigations of the last twenty years have shown that the lower mammalian brain plays a fundamental role in emotional behaviour. . . . It has a greater capacity than the reptilian brain for learning new approaches and solutions to problems on the basis of immediate experience. But like the reptilian brain, it does not have the ability . . . to put its feelings into words. [16]
In the remainder of this chapter I shall lean heavily on MacLean's experimental work and theoretical conclusions (though deviating from the latter in minor details). The great attraction of the theory is its consistently hierarchic approach, in the sense in which this term is used in the present book. 'In its evolution', he writes, 'the brain of man retains the hierarchical organisation of the three basic types which can be conveniently labelled as reptilian, paleo-mammalian and neo-mammalian. The limbic system [see below] represents the paleo-mammalian brain, which is an inheritance from lower mammals. Man's limbic system is much more highly structured than that of lower animals, but its basic organisation, chemistry, etc., are very similar. The same may be said of the other two basic types. And there is ample evidence that all three types have their own special subjective, cognitive (problem-solving) memory and other parallel functions.' [17] We can paraphrase this by saying that each functions as a relatively autonomous holon on its own level.
I shall not burden the reader with a disquisition on brain anatomy, but a few remarks about the evolution of the brain may be helpful at this point. The ancient anatomists compared the brain to a fruit like an orange: the central part is like the pulp, the outer like the rind; so the former was named medulla, the latter cortex. The medulla is a prolongation of the spinal cord, and is further prolonged into the brain-stem. Inside or near to it are clusters and structures of cell masses such as the hypothalamus, the reticular system, the basal ganglia. This is the phylogenetically oldest part of the brain, its core or chassis, roughly corresponding to the basic structures of the reptile's brain. It contains the essential apparatus for internal (visceral and glandular) regulations, for primitive activities based on instincts and reflexes, and also the centres for arousing the animal's vigilance or putting it to sleep. The cortex or rind, on the other hand, is the apparatus for 'intelligent' behaviour, from the capacity to acquire new responses by whatever primitive form of learning, up to conceptual thought. The cortex emerges at the stage of evolutionary history when the amphibians began to turn into reptiles; the first promising cortical divisions are found in the turtle. The cortex is the surface-layer of the cerebral hemis
pheres which grow out of the brain-stem and fold around it like a cloak or mantle (hence 'pallium'). It consists of the outer, 'grey' cortical layer of cell bodies, and the white fibres underlying it. The human cortex is about a tenth of an inch thick and contains about ten thousand million neurons densely packed together, covering an area of about three square feet, crammed into the gyri and sulki, convolutions and invaginations of the crinkled sheet. Truly a staggering feat of circuitry -- and yet . . .
The old anatomists' analogy of the orange helps one to get a rough idea of the basic structure of the brain; but beyond that it becomes misleading. The cortex, unlike the rind of the orange, is not homogeneous. Different types of nerve cells dominate in different functional areas; and more than a hundred different areas have been mapped, numbered, or named according to their microscopic structure and other criteria. But although the details of these classifications are controversial, there is general agreement that, judged by their evolutionary history and by their distinctive texture, the cortex has three basic sub-divisions. The older anatomists called them archipallium, paleopallium and neopallium; MacLean calls them archicortex, mesocortex and neocortex, co-ordinated respectively with the reptilian, primitive mammalian and neo-mammalian brain. But the spatial arrangement of these three main cortical divisions inside our skulls is not easy to explain or visualise; MacLean proposed a simplified model in the form of an inflatable toy balloon with three distinct segments (Figure 12). [18]
A, M and N stand for archi, meso and neo cortex. 'The uninflated balloon represents the situation found in the amphibian. With the appearance of the reptile, there is a ballooning out of the archicortex and a considerable expansion of the mesocortex. During the phylogeny of the mammal, one of the most striking events of all evolution occurs. This is the great ballooning out of the neocortex. In the process, the archicortex and the greater part of the mesocortex are folded like two concentric rings into the limbic lobe and are relegated, as it were, to the cellar of the brain' (Figure 13). [19]
The result of this folding-in process is shown in Figure 13, where (a) is a side-view, and (b) a vertical cross-section of a monkey's brain. The two in-folded rings together form a large convolution, the so-called limbic lobe of the cerebral cortex, shown in black. 'Limbic' means 'hemming in', 'forming a border around'; the term was coined in 1878 by the great brain-mapper, Broca, because the limbic convolution surrounds the brain-stem -- the central core (not shown on the diagram). In fact, the limbic cortex is so closely connected to the brain-stem that together they constitute a functionally integrated system -- the 'limbic system' with its 'reptilian' and 'primitive-mammalian' features. The limbic system may thus be loosely called the 'old brain', in contrast to the 'neocortical system' or 'new brain'.
Already Broca had demonstrated that 'the great limbic lobe is found as a kind of common denominator in the brains of all mammals. . . . The faithful preservation of this cortex through the phylogeny of the mammals contrasts with the rapid evolution and growth of the neocortex around it, the latter representing the growth of intellectual function. . . . The limbic cortex is structurally primitive compared to the neocortex; it shows essentially the same degree of development and organisation throughout the mammalian series. This would suggest that it functions on an animalistic level in both animal and man.' [20]
Emotion and the Ancient Brain
This is surely an odd state of affairs. If the evidence had not taught us the contrary, we would expect an evolutionary development which gradually transformed the primitive old brain into a more sophisticated instrument -- as it transformed claw into hand, gill into lung. Instead, evolution superimposed a new, superior structure on an old one, with partly overlapping functions, and without providing the new with a clear-cut, hierarchic control over the old -- thus inviting confusion and conflict. Let us have a closer look at this dichotomy between the limbic and neocortical systems.
MacLean compares the cortex with a television screen that gives the animal a combined picture of the outside and inside worlds. This is a useful analogy for the limited purpose for which he employs it. But to avoid misunderstandings I would like, before making use of it, to point out its limitations. Of all parts of the body the cerebral cortex is the most intimately connected with awareness and self-awareness; but it would be wrong to call it -- as is sometimes done -- the seat of awareness. To quote that wise mechanist, Judson Herrick: 'The search for a seat of consciousness in general or of any particular kind of conscious experience is a pseudo-problem because the conscious act has properties that are not definable in terms of the spatial and temporal units which are employed in the measurement of the objects and events of our objective world. What we search for and find by objective inquiry is the apparatus which generates awareness. This mechanism has locus in space and time, but the awareness as such is not located in any particular part of the mechanism' (my italics). [21]
In this sense, then, the cerebral cortex is probably the principal 'apparatus which generates awareness'. The ancient structures in the brain-stem may be said to provide the 'raw material' of awareness: the reticular formation 'arouses' the animal; the hypothalamic structures contribute the visceral component; but ultimately 'the cerebral cortex is to the brain what the television screen is to the television set and what a radar screen is to the pilot'. [22] If this is the case, we must face the paradox that evolution has provided us with at least two such screens, one ancient, one new.
The ancient, limbic screen has, as we have seen, three principal characteristics: (a) its microscopic structure is coarse and primi- tive compared to the neocortex; (b) its basic pattern is still essentially the same as in the lower mammals; (c) in contrast to the new cortex, the limbic system is intimately connected by two-way neural pathways -- fibres as thick as a pencil -- with the hypothalamus and other centres in the brain-stem concerned with visceral sensations and emotional reactions including sex, hunger, fear and aggression; so much so that the limbic system once bore the name 'the visceral brain'.* The term was changed because it gave the impression that it was only concerned with the viscera; whereas in fact the ancient, limbic cortex, as we shall presently see, also has its own mental processes: it emotes and thinks -- though not in verbal concepts.
* Even earlier the limbic cortex was called the rhinencephalon, i.e., small brain, because it was thought to be exclusively concerned with smell.
The limbic system may be compared to a primitive television screen which combines, and often confuses, projections from the internal, visceral environment with the external environment. 'Such a cortex must have offered some of the confusion of a twice-exposed film. In any event, it could not have been altogether satisfactory, because when Nature proceeded to develop the neo-mammalian brain, she constructed progressively a bigger and finer type of screen, which gave predominantly a picture of the outside world made up of impressions from the eye, the ear and the surface of the body. . . . But Nature in her frugality did not discard the old screen. Since it seemed adequate for smelling, tasting and feeling what is going on inside the body, she has kept the ftlaments in the tube of the old screen glowing night and day.' [23]
However, the old brain is not merely concerned with taste, smell and visceral sensations, leaving the new to turn its gaze outward: that would be an idyllic distribution of labour. The 'Papez theory of emotions' originated in the study of pathological conditions in which the 'old tube' interferes with the new, and tends to usurp its functions. Papez noted that damage to the limbic system caused a variety of symptoms, which primarily affected the emotional behaviour of animal and man. An extreme case is the terrible disease of rabies, whose virus appears to have a predilection for the limbic system, and in which 'the patient is subject to paroxysms of rage and terror'. [24] Less extreme but equally telling are the emotional states in the 'sacred disease', epilepsy. Hughlin Jackson, one of the pioneers of neurology, described the epileptic aura preceding the attack as the 'dreamy state', a kind of 'double consciousness', in which the pat
ient is aware of the reality around him, but as if it were a dream, or a repetition o[ something that happened before (déjà vu). During the actual fit of psycho-motor epilepsy, the 'animalistic' brain seems to take over the personally. Biting, chewing and grinding the teeth, terror or furore are well-known distressing accompaniments of the fit, of which as a rule the sufferer retains no memory. All the clinical evidence points in these cases to the limbic system as the focus of the epileptic discharge. [25] Typical of the clinical material is, for instance, the case of. a nymphomaniac woman of fifty-five 'who, for more than ten years, complained of a persistent "passionate feeling." Later she developed convulsions. It is notable that perfume was thought to exaggerate her symptoms' [26] -- smell is the most 'visceral' of the senses. She underwent brain surgery, and the operation revealed a lesion affecting the limbic lobe.